Background. The term “aggressive pituitary adenoma” arose as a result of transforming the term “atypical pituitary adenoma”, which was used in WHO classification for pituitary adenomas with specifications of higher labeling index Ki-67 (≥3 %) and increased number of mitoses with expression of the p53 proteins. However, not all tumors with these features were aggressive, and currently, according to the European Society of Endocrinology Clinical Practice Guideline for the management of aggressive pituitary tumors and carcinomas (2018), aggressive pituitary tumors are labeled as tumors that have invasive and unusually rapid or clinically significant growth which occurs despite the use of standard treatment protocols (pharmacological, surgical and radiation). Till date, there are numerous papers in literature describing various schemes and indications for the use of temozolomide. The efficiency of ongoing therapy, according to different authors, varies from 29 to 81 %, with an average effectiveness ranging between 40–45 %. Aim. To present our own experience of using temozolomide in the treatment of patients with aggressive pituitary tumors. Materials and methods. Three patients were included in the study, one male (45 years old) and 2 females (61 and 29 years old). All three patients included in the study first underwent surgical resection followed by radiation therapy if no response / hormonal activity didn’t resume. The decision to start temozolomide protocol was held by concerned medical commission under supervision of local ethical committee. Results. All patients responded well to temozolomide therapy with decrease in the size of tumor and decrease in levels of prolactin in cases of prolactinoma. Conclusion. The most important step in treating patients with aggressive pituitary adenomas is their early diagnosis, which could be possible only if the specific identifying markers of aggressiveness were found, which unfortunately are not found yet.
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